1. Field of the Invention
This invention relates to electronic systems, and more particularly, to the reduction of cross-talk between signal lines in electronic systems.
2. Description of the Related Art
One important consideration in the design of electronic systems is the affect of noise on the various signal paths. Noise in an electronic system may be defined by the deviation of a signal from its intended or ideal value. Such deviations may be caused by a number of factors, such as power supply bounce due to simultaneous switching, cross talk between signal lines, and electromagnetic energy produced by other sources. Designing a properly functioning electronic system requires that the effects of the various types of noise be reduced to the maximum extent possible.
One signaling convention that is useful in reducing noise from cross talk or electromagnetic energy from other sources is that of differential signaling. Differential signaling is well known in the art, and involves two signal lines that convey complementary states (with respect to each other) of the same signal. Since the two signal lines that convey a differential signal are typically in close physical proximity to each other, noise in the vicinity tends to effect both of them equally, the overall effect of the noise tends to be cancelled out.
Problems may arise when a number of differential signal lines are placed within close physical proximity of each other. For example, crosstalk can occur between two differential signal lines that are not part of the same differential pair but are nevertheless adjacent to each other. When this occurs, it is possible that the differential signal lines of their respective pairs may not be affected equally. Thus, such noise may adversely affect differential signals and may lead to erroneous operation of the electronic system.